What does obj_now_BVHtree.overlap(obj1,obj2) return?
mathutils.bvhtree.BVHTree.overlap returns a list of unique tuples, where each tuple represents the overlap between two elements of the two trees. The first entry of each tuple is the index from one tree and the second entry is from the other tree.


  overlap(other_tree)
  
  Find overlapping indices between 2 trees.
  
  
  Parameters: other_tree(BVHTree) – Other tree to perform overlap test on. 
  Returns: Returns a list of unique index pairs, the first index referencing this tree, the second referencing the other_tree.
  Return type: list